> My suggestion is, that the great amount of sponges is responsible for
> the underprocessing. I think the tissue was'nt dehydratet enough and
> water was taken over from one step to the next.

dear Gudrun,

we also had this problems a couple of time ago, I think, you are absoletely
right considering the tight packing of sponges. But there's another big
problem using sponges: there can produce peculiar triangular holes,
artifacts, which can be seen sometimes especially in soft tissue, f.e.
breast biopsies. For that reason we changed the processing and use now
perforated paper from VOGEL (Filterpapier fuer Einbettkassetten, 66x26mm)
for years.

If you want to know further details, please contact me (01-91021-86411).

article on this topic:

Arch Pathol Lab Med. 1990 Dec;114(12):1285-7. 
Sponge artifact in biopsy specimens.
Landas SK, Bromley CM.

We describe a sponge-induced artifact in histologic sections of small biopsy
specimens. The artifacts are angulated, often triangular holes within the
tissue. They appear to be introduced as individual sponge barbs become
embedded in the perimeter of biopsy specimens during tissue processing. The
artifact is generally of little importance, but in certain specimens, such
as needle biopsies of the kidney or liver, it may occasionally obscure
important information. Other methods, such as lens paper wrapping, may be
superior in these situations. The utility of the tissue cassette sponge, in
most situations, outweighs the artifact.

Alexander Nader MD
Institut for Pathology, Hanusch-Krankenhaus
Vienna, Austria

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